Various attempts have been made to solve these problems mentioned above. For example, F. Strasser et al disclose in their invention (U.S. Pat. No. 4,410,285) a sliding member formed of an outer metal ring and an inner bearing of a ceramic material, and a ring of a metal felt located between the metal ring and the ceramic material ring.
F. R. Marrison et al give the results from their studies (Lubrication Engineering, vol. 40.3, 153-159) wherein the fatigue property of ceramic balls of Si.sub.3 N.sub.4 and steel bearings was measured in detail.
The above disclose the use of ceramics in combination with a metal.
J. Lammer et al disclose in their invention (U.S. Pat. No. 4,522,453) a sliding member formed of a member coated with TiC and a member coated with TiN.
Yamamoto et al disclose in their invention (Japanese Patent No. S55-100421) that a sliding member comprises a member of sintered Si.sub.3 N.sub.4 and a member of sintered SiC, is capable of using in non-lubricated condition and less wearing. They are the combination of ceramics.
Silicon nitride type sintered ceramic materials have found popular recognition as sintered ceramic materials of large mechanical strength. Unfortunately, the silicon nitride type sintered ceramic materials produced by the metal silicon nitriding method, the imide method, etc. and offered generally in the market fail to satisfy the levels of mechanical strength, resistance to thermal shock, and resistance to corrosion which sliding members destined to serve in atmospheres of elevated temperatures.